Production of anhydrous calcium grease



nite States Patent PRODUTION 0F DROUS CALCIUM GREASE Martin M. McCormick, Chicago, and John W. Nelson, Lansing, 111., assignors to Sinclair Refining Company, New York, N. Y., a corporation of Maine No Drawing. Application July 8, 1954 Serial No. 442,198

3 Claims. (Cl. 252-39) Our invention relates to greases and more particularly relates to methods for the manufacture of anhydrous calcium grease.

The usual processes for preparing anhydrous calcium greases are characterized by lengthy reaction times and violent foaming and generally produce lumpy greases having high soap contents for a given penetration. Lengthy reaction times constitute inefiicient use of equipment. Foaming necessitates the employment of larger equipment than would be sufficient ordinarily to contain the reaction mass. Lumps in a grease necessitate a special milling step to obtain homogeneous greases, and frequently even milling may not remove all lumps satisfactorily. And, of course, high soap content constitutes poor yield when it is possible to obtain a high quality grease of the same consistency with a lower soap content.

We have now discovered in the preparation of anhydrous calcium greases, in contrast with the prior art methods, that forming the soap in the presence of defined amounts of water and oil added at the initiation of the soap forming step and adding further quantities of oil following partial dehydration of the soap-oil mixture in conjunction with the use of low temperatures throughout the grease making procedure results in high yields of smooth greases, and the process is characterized by short reaction time and an absence of foaming during its course.

By our method foaming is eliminated, high yields of smooth greases result, processing time is about 3 to 6 hours rather than the usual 12 or more hours and greases containing to 25 weight percent soap and of all of the NLGI grades can be produced. In addition to these advantages other economies are effected by our novel process such as the savings attendant upon the use of lower temperatures, the increased capacity of greasemaking equipment by virtue of the shortened reaction time, the increased yields and the absence of foaming.

According to the method of our invention lime, solid fatty acid, water and oil are mixed at a low temperature, for example ambient temperature or about 70 to about 110 F., and then heated. Thickening will generally occur at temperatures of about 120 to 145 F. during which time cloudy water begins to appear around the grease kettle at the edge of the grease. The temperature is gradually raised to about 190 F. while the reaction goes to substantial completion; completion of the reaction is indicated by the change in color of the free water from cloudy to clear. Upon completion of the reaction, the mass is partially dehydrated at a temperature of about 190 to 225 F., that is, the free water is evaporated. After evaporation of the free water, additional oil is added while continuing the heating. After addition of the oil the reaction mass is dehydrated substantially completely at a temperature below about 260 F. and preferably in the range of about 240 to 255 F. When dehydration is complete heating is stopped and any additional oil needed or desired is blended into the mixture until the product shows the desired penetration. The

2,83 1,8 l i Patented Apr. 22, 1058 product can be used as such, though it is preferred to mill the grease to insure uniform consistency.

The quantity of water initially added in our novel process is about 0.25 to 2.0 parts by weight per part of the fatty component of the grease with about 0.5 to 1.0 parts of water being preferred. By employing water in the defined quantities'initiation of the reaction at low temperatures, i. e., about 130 F., is facilitated, and the greases produced are characterized by water stability. Equally important in our process is control of the ratio of starting oil to fatty component; we have found ratios (parts by weight) of about 2 to 4:1 to be highly satisfactory and prefer a 3:1 ratio. About 3 parts (by weight) to all of the remainder of the oil to be employed in the final grease, and preferably about 5 parts, is added to the thickened soap-starting oil reaction mass after partial dehydration, i. e., removal of free water. This oil is preferably added slowly to avoid abruptly thinning the reaction mass. This oil can be added all at one time Without deleteriously aifecting the quality of the grease prodnot; however, we have found it desirable to add the oil incrementally to avoid any possibility of excessive foaming. Upon complete dehydration of the reaction mass any oil remaining is added to adjust the grease to the desired end properties.

Mineral lubricating oils, such as neutral oils, and synthetic oils normally used in calcium grease manufacturing processes can be used in our process. We prefer to employ a blend of solvent-refined Mid-Continent crudes having a viscosity of about SUS at F. The lime employed can be in any of the forms usually employed in grease manufacture, i. e., calcium oxide, calcium hydroxide, hydrated calcium oxide, calcium carbonate, etc., and is present in amounts ranging from about the stoichiometric amount to about a 10% excess. The various hydroxy stearic acids, such as 9-hydroxy stearic acid, 9,10-dihydroxy stearic acid and the like, can be employed; the preferred fatty component is IZ-hydroxy stearic acid.

The method of our invention will be illustrated by the following example:

EXAMPLE I Twenty pounds of 12-hydroxy stearic acid, 10 pounds of water, and sixty pounds of mineral oil containing 2.9 pounds of hydrated lime previously slurried in part of this oil were mixed in a steam heated kettle at 100 F. The mineral oil used was an 82 SUS/ 100 F. blend of 80 volume percent solvent treated Mid-Continent neutral and 20 volume percent conventionally refined naphthenic base Coastal stock. The temperature was raised gradually and at about F. a pronounced thickening occurred indicating reaction. The initial formation of a smooth soap took place in the heterogeneous phase system at a temperature well below the melting point of the acid. i. e., below about F., as indicated by presence of a few solid acid flakes on the kettle walls where temperature was maximum. During formation of the smooth, homogeneously thickened mass in the temperature range 130 to F. free water was rejected, appearing at the surface and edge of the reaction mass in the kettle. The separated free water changed from cloudy to clear, show ing essentially complete reaction of the lime and acid. The temperature was raised from 190 F. to 225 F. to evaporate visible non-emulsified Water in order to preclude later foaming. An additional five parts of the oil blend (based on weight of fatty acid employed) was incorporated while raising the temperature from 225 to 240 F. Dehydration in the temperature range of 225 to 240 F. was accompanied by gradual, smooth gel formation. The temperature was then raised to about 250 to 255 F. and

held one hour to insure complete dehydration after which the grease was cooled to 170 F. while incorporating the remainder of the oil (90 pounds) and about 1.35 pounds of diphenyl amine oxidation inhibitor. The grease was then milled at 170 F., 0.005 inch clearance and a flow rate of 1.5 pounds per minute in a conventional colloid mill.

The process of Example I was characterized by a complete absence of foaming. The anhydrous grease produced was analyzed and tested for penetration according to the standard tests specified by the American Society for Testing Materials with the following results.

Table I From the foregoing it is apparent that we have discovered a process which produces high quality grease in an economical and eificient manner.

We claim:

1. In the preparation of anhydrous calcium grease compositions wherein a mineral lubricating oil is thickened to grease consistency with a calcium hydroxy stearate, the steps of forming a heterogeneous mixture, at a temperature from about room temperature to 110 F., of hydroxy stearic acid, lime to saponify the fatty component and form a soap, about 0.2 to 2.0 parts by weight of water based on the fatty component and about 2 to 4 parts by weight of a mineral lubricating oil based on the fatty component, heating the mixture to provide a thickening of the oil at about 120 F. to 145 F. and an initial formation of soap below the melting point of the acid, raising the temperature to about 190 F. while the saponification goes to substantial completion, evaporating free water from the mass, adding from about 3 parts to the total amount of the remainder of the oil of the final composition and then dehydrating the grease at a maximum temperature of below about 260 F.

2. In the preparation of anhydrous calcium grease compositions wherein a mineral lubricating oil is thickened to grease consistency with calcium 12-hydroxy stearate, the steps of adding, at a temperature from about room temperature to F., the 12-hydroxy stearic acid to a slurry containing about a stoichiometric quantity of lime to saponify the IZ-hydroxy stearic acid, about 0.5 part by weight of water and about 3 parts by weight of a mineral lubricating oil each based on the 12-hydroxy stearic acid, elevating the temperature whereby thickening begins occurring at about F. and free water begins to form, raising the temperature to about 190 F. While the saponification goes to substantial completion, evaporating the free water at a temperature above about 190 F. while elevating the temperature to about 225 F., incorporating additional mineral lubricating oil until about 5 parts by weight based on the 12-hydroxy stearic acid have been added, dehydrating the reaction mass at a temperature between about 240 and 255 F., and then adding the remainder of the oil of the final composition while permitting the grease to cool. i

3. In the preparation of anhydrous calcium grease compositions wherein a lubricating oil is thickened to grease consistency with a calcium hydroxy stearate, the steps of forming a heterogeneous mixture, at a temperature from about room temperature to 110 F., of hydroxy stearic acid, lime to saponify the fatty component and form a soap, about 0.2 to 2.0 parts by weight of water based on the fatty component and about 2 to 4 parts by weight of a lubricating oil based on the fatty component, heating the mixture to provide a thickening of the oil at about 120 F. to F. and an initial formation of soap below the melting point of the acid, raising the temperature to about F. while the saponification goes to substantial completion, evaporating free water from the mass, adding from about 3 parts to the total amount of the remainder of the oil of the final composition and then dehydrating the grease at a maximum temperature of below about 260 F.

References Cited in the file of this patent UNITED STATES PATENTS 2,607,734 Sproule et a1 Aug. 19, 1952 2,607,735 Sproule et a1. Aug. 19, 1952 2,613,182 Sproule et al. Oct. 7, 1952 2,618,599 King et a1. Nov. 18, 1952 

1. IN THE PREPARATION OF ANHYDROUS CALCIUM GREASE COMPOSITIONS WHEREIN A MINERAL LUBRICATING OIL IS THICKENED TO GREASE CONSISTENCY WITH A CALCIUM HYDROXY STEARATE, THE STEPS OF FORMING A HETEOGENEROUS MIXTURE, AT A TEMPERATURE FROM ABOUT ROOM TEMPERATURE TO 110*F., TO HYDROXY STEARIC ACID, LIME TO SAPONIFY THE FATTY COMPONENT AND FORM A SOAP, ABOUT 0.2 TO 2.0 PARTS BY WEIGHT OF WATER BASED ON THE FATTY COMPONENT AND ABOUT 2 TO 4 PARTS BY WEIGHT OF A MINERAL LUBRICATING OIL BASED ON THE FATTY COMPONENT, HEATING THE MIXTURE TO PROVIDE A THICKENING OF THE OIL AT ABOUT 120*F, T 145*F. AND AN INITIAL FORMATION OF SOAP BELOW THE MELTING POINT OF THE ACID, RAISING THE TEMPERATURE TO ABOUT 190*F. WHILE THE SAPONIFICATION GOES TO SUBSTANTIAL COMPLETION, EVAPORATING FREE WATER FROM THE MASS, ADDING FROM BOUT 3 PARTS TO THE TOTAL AMOUNT OF THE REMAINDER OF THE OIL OF THE FINAL COMPOSITION AND THEN DEHYDRATING THE GREASE AT A MAXIMUM TEMPERATURE OF BELOW ABOUT 260*F. 